Sugar-containing water-absorbing composition which facilitates fiber formation

ABSTRACT

A copolymer of recurring units of at least one α,β-unsaturated monomer and recurring units of at least one copolymerizable comonomer comprising, in its preferred embodiment from about 20 to about 80 percent pendant carboxylic acid units and from about 80 to about 20 percent pendant carboxylate salt units, is blended with at least one disccharide or oligosaccharide to produce a water-absorbing composition upon curing. The composition is particularly suitable for fiber formation.

This invention relates to water-absorbing compositions.

In one of its more specific aspects, this invention relates to theincorporation of water-absorbing compositions into articles ofmanufacture for the purpose of improving the absorbent properties of thearticles.

Absorbent compositions are widely used in the manufacture of productswhich require high absorption capability. For example, water-absorbingcompositions are used in the manufacture of surgical and dental sponges,tampons, sanitary napkins and pads, bandages, disposable diapers, meattrays, and household pet litter. Water-absorbing compositions are alsoused for the modification of soil to improve water retention andincrease air capacity and for a host of other applications.

As used herein, the term "water" when used in the phrases"water-absorbing" and "water-absorbent" is understood to mean not onlywater but also electrolyte solutions such as body fluids.

A number of absorbent compositions have been developed which exhibitwater absorption capacity. For example, U.S. Pat. Nos. 3,954,721 and3,983,095 disclose preparations for derivatives of copolymers of maleicanhydride with at least one suitable vinyl monomer in fibrous form. Thefibrous copolymers are rendered hydrophilic and water-swellable byreaction with ammonia or an alkali metal hydroxide. U.S. Pat. No.3,810,468 discloses lightly cross-linked olefin-maleic anhydridecopolymers prepared a substantially linear copolymers and then reactedwith a diol or a diamine to introduce cross-linking. The resultantlightly cross-linked copolymers are treated with ammonia or an aqueousor alcohol solution of an alkali metal hydroxide. U.S. Pat. No.3,989,586 describes the preparation of sorptive paper products byincorporating cross-linked copolymers of styrene or olefins with maleicanhydride in a paper web which is then treated to convert the copolymerto a water-swellable salt form. U.S. Pat. No. 3,980,663 describeswater-swellable absorbent articles made from carboxylic polyelectrolytesvia cross-linking with glycerine diglycidyl ether. U.S. Pat. Nos.4,332,917 and 4,338,417 disclose blends of copolymers of styrene andmaleic anhydride with polymers derived from a monomeric ester havingvinyl unsaturation e.g., poly(vinyl acetate), cellulose triacetate,cellulose aceto-butyrate, poly(ethyl acrylate) andpoly(methylmethacrylate). U.S. Pat. No. 4,420,588 teaches awater-absorbing rubber composition comprising a 1,3-diene rubber and awater-absorbing resin dispersed in the rubber. And, U.S. Pat. No.4,155,957 teaches a self-swelling, leakage-preventing rubber materialwhich comprises (1) a copolymer of a lower olefin with maleic anhydride;(2) a polymer emulsion which is compatible with copolymer (1), e.g., anethylene-vinyl acetate copolymer emulsion; and (3) a polyhydric orpolyfunctional compound.

The desirability of having water-absorbing compositions in fibrous formsis well known. For example, in sanitary products such as disposablediapers and tampons, fibers can be more easily confined within theproduct. In this respect, the prior art water-absorbing compositions aredeficient; they do not facilitate fiber formation. Because of the speedof their crosslinking reactions, the prior art water-absorbingcompositions possess no appreciable shelf life; fiber formation must becompleted shortly after the compositions are prepared. This shelf lifedeficiency in the prior art compositions is discussed in U.S. Pat. No.3,983,095 which teaches that fiber formation should be completed withinseveral hours and in some cases immediately, depending upon thereactivity of the cross-linking agent used.

The water-absorbing compositions of this invention possess excellentshelf life and have been found suitable for forming into fibers severalmonths after preparation. They facilitate fiber formation over a widerange of time and temperature. They also possess excellent integrity inthe hydrogel or water-swollen state, exhibit excellent water andelectrolyte solution absorption capacity, and are readily incorporatedinto conventional water-absorbing products using conventional methods.

According to this invention there is provided a composition which iswater-absorbent upon curing comprising (a) a copolymer containing fromabout 25 to about 75 mole percent of at least one α, β-unsaturatedmonomer bearing at least one pendant unit selected from the groupconsisting of carboxylic acid units and derivatives of carboxylic acidunits and from about 75 to about 25 mole percent of at least onecopolymerizable comonomer, wherein from about 20 to about 80 percent ofthe total pendant units introduced through the α, β-unsaturated monomerare carboxylic acid units or must be converted into carboxylic acidunits, and wherein from about 80 to about 20 percent of the totalpendant units are carboxylate metal salt units or must be converted intocarboxylate salt units; and (b) at least one carbohydrate compoundselected from the group consisting of disaccharides andoligosaccharides.

According to this invention there is provided a method of producing awater-absorbing composition comprising the steps of: (a) preparing ablend of (i) a copolymer containing from about 25 to about 75 molepercent recurring units of at least one α, β-unsaturated monomer whichbears at least one pendant unit selected from the group consisting ofcarboxylic acid units and derivatives of carboxylic acid units, and fromabout 75 to 25 mole percent recurring units of at least onecopolymerizable comonomer, wherein from about 20 to about 80 molepercent of the total pendant units introduced through the recurring α,β-unsaturated monomer units are carboxylic acid units or must beconverted into carboxylic acid units and wherein from about 80 to about20 percent of the total pendant units are carboxylate salt units or mustbe converted into carboxylate salt units; and (ii) at least onecarbohydrate compound selected from the group consisting ofdisaccharides and oligosaccharides; and (b) curing the resulting blend.

According to this invention there is provided a method of absorbingwater and electrolyte solutions comprising the step of contacting thewater or electrolyte solution to be absorbed with a curedwater-absorbing composition comprising a blend of: (a) a copolymercontaining from about 25 to about 75 mole percent of at least one α,β-unsaturated monomer bearing at least one pendant unit selected fromthe group consisting of carboxylic acid units and derivatives ofcarboxylic acid units and from about 75 to 25 mole percent of at leastone copolymerizable comonomer, wherein from about 20 to about 80 percentof the total pendant units introduced through the α, β-unsaturatedmonomer are carboxylic acid units or must be converted into carboxylicacid units, and wherein from about 80 to about 20 percent of the totalpendant units are carboxylate salt units or must be converted intocarboxylate salt units; and (b) at least one carbohydrate compoundselected from the group consisting of disaccharides andoligosaccharides.

An article of manufacture comprising a cured water-absorbing compositionand a means for supporting said composition to present said compositionfor absorption usage, wherein said water-absorbing composition comprisesa blend of: (a) a copolymer containing from about 25 to about 75 molepercent of at least one α, β-unsaturated monomer bearing at least onependant unit selected from the group consisting of carboxylic acid unitsand derivatives of carboxylic acid units and from about 75 to about 25mole percent of at least one copolymerizable comonomer, wherein fromabout 20 to 80 percent of the total pendant units introduced through theα, β-unsaturated monomer are carboxylic acid units or must be convertedinto carboxylic acid units, and wherein from about 80 to about 20percent of the total pendant units are carboxylate salt units or must beconverted into carboxylate salt units; and (b) at least one carbohydratecompound selected from the group consisting of disaccharides andoligosaccharides.

According to this invention there is also provided a method of enhancingat least one water-absorbing characteristic of an article which methodcomprises the step of incorporating into the article a curedwater-absorbing composition comprising a blend of: (a) a copolymercontaining from about 25 to about 75 mole percent of at least one α,β-unsaturated monomer bearing at least one pendant unit selected fromthe group consisting of carboxylic acid units and derivatives ofcarboxylic acid units and from about 75 to about 25 mole percent of atleast one copolymerizable comonomer, wherein from about 20 to about 80percent of the total pendant units introduced through the α,β-unsaturated monomer are carboxylic acid units or must be convertedinto carboxylic acid units, and wherein from about 80 to about 20percent of the total pendant units are carboxylate salt units or must beconverted into carboxylate metal salt units; and (b) at least onecarbohydrate compound selected from the group consisting ofdisaccharides and oligosaccharides said composition being incorporatedinto the article in an effective amount to enhance at least onewater-absorbing characteristic of the article as compared to thewater-absorbing characteristics of the article in the absence of thecomposition.

Copolymers suitable for use to produce water-absorbing compositions ofthe invention will contain from about 25 to about 75 total mole percentrecurring units of at least one α, β-unsaturated monomer and from about75 to about 25 total mole percent recurring units of at least onecopolymerizable comonomer. Preferably, the copolymer will contain fromabout 35 to about 65 total mole percent of recurring units of at leastone α, β-unsaturated monomer and from about 65 to about 35 total molepercent of at least one copolymerizable comonomer. Most preferably, thecopolymer will be an equimolar copolymer.

Suitable α, β-unsaturated monomers are those bearing at least onependant carboxylic acid unit or derivative of a carboxylic acid unit.Derivatives of carboxylic acid units include carboxylic acid saltgroups, carboxylic acid amide groups, carboxylic acid imide groups,carboxylic acid anhydride groups and carboxylic acid ester groups.

Suitable α, β-unsaturated monomers include maleic acid; crotonic acid;fumaric acid; mesaconic acid; the sodium salt of maleic acid; the sodiumsalt of 2-methyl, 2-butene dicarboxylic acid; the sodium salt ofitaconic acid; maleamic acid; maleamide; N-phenyl maleimide; maleimide;maleic anhydride; fuameric anhydride; itaconic anhydride; citraconicanhydride; mesaconic anhydride; methyl itaconic anhydride; ethyl maleicanhydride; diethylmaleate; methylmaleate; and the like, and theirmixtures.

Any suitable copolymerizable comonomer can be employed. Suitablecopolymerizable comonomers include ethylene, propylene, isobutylene, C₁to C₄ alkyl methacrylates, vinyl acetate, methyl vinyl ether, isobutylvinyl ether, and styrenic compounds having the formula: ##STR1## whereinR represents hydrogen or an alkyl group having from 1 to 6 carbon atomsand wherein the benzene ring may be substituted with low molecularweight alkyl or hydroxy groups.

Suitable C₁ to C₄ alkyl acrylates include methyl acrylate, ethylacrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, andthe like, and their mixtures.

Suitable C₁ to C₄ alkyl methacrylates include methyl methacrylate, ethylmethacrylate, isopropyl methacrylate, n-propylmethacrylate, n-butylmethacrylate, and the like, and their mixtures.

And, suitable styrenic compounds include styrene, α-methylstyrene,p-methylstyrene, t-butyl styrene, and the like, and their mixtures.

The pendant units on the α, β-unsaturated monomer, will determine what,if any, additional reactions must be carried out to obtain a copolymerhaving the requisite pendant units necessary to produce thewater-absorbing compositions of this invention about 20 to about 80percent pendant carboxylic acid units and about 80 to about 20 percentpendant carboxylate salt units. Preferably, both units are present in anamount of from about 30 to about 70 percent.

In general, if the α, β-unsaturated monomer bears only carboxylic acidamide, carboxylic acid imide, carboxylic acid anhydride, carboxylic acidester groups, or mixtures thereof, it will be necessary to convert atleast a portion of such carboxylic acid derivative groups to carboxylicacid groups by, for example, a hydrolysis reaction. If the α,β-unsaturated monomer bears only carboxylic acid salt groups,acidification to form carboxylic acid groups will be necessary.

Similarly, the final copolymer must contain from about 80 to 20 percentpendant carboxylate salt units. Accordingly, it may be necessary tocarry out a neutralization reaction. Neutralization of carboxylic acidgroups with a strong organic or inorganic base such as NaOH, KOH,ammonia, ammonia-in-water solution, or organic amines will result in theformation of carboxylate salt units, preferably carboxylate metal saltunits.

Moreover, the sequence and the number of reactions (hydrolysis,acidification, neutralization, etc.) carried out to obtain the desiredfunctionality attached to copolymer backbone are not critical. Anynumber and sequence resulting in a final copolymer which possesses fromabout 20 to about 80 percent pendant carboxylic acid units and fromabout 80 to about 20 percent pendant carboxylate salt units is suitable.

One copolymer particularly suitable for use is a copolymer of maleicanhydride and isobutylene. Another is maleic anhydride and styrene.Suitable copolymers will have peak molecular weights of from about 5,000to about 500,000 or more.

Suitable copolymers of maleic anhydride and isobutylene can be preparedusing any suitable conventional method. Such copolymers are alsocommercially available from Kuraray Isoprene Chemical Company, Ltd.,Osaka, Japan under the trademark ISOBAM. ISOBAM copolymers are availablein several grades which are differentiated by viscosity molecularweight: ISOBAM-10, 160,000 to 170,000; ISOBAM-06, 80,000 to 90,000;ISOBAM-04, 55,000 to 65,000; and ISOBAM-600, 6,000 to 10,000.

To produce a water-absorbing composition of this invention, at least onecopolymer as described above and at least one carbohydrate compoundselected from the group consisting of disaccharides and oligosaccharidesare blended such that the water-absorbing composition contains in weightpercent, from about 80 to about 99 total copolymer and from about 1 toabout 20 total carbohydrate compound. Preferably, the composition willcontain from about 85 to about 95 weight percent total copolymer andfrom about 5 to about 15 weight percent total carbohydrate compound.

Any suitable disaccharide or oligosaccharide can be employed in thepractice of this invention.

Disaccharides consist of two simple sugar units bound together by aglycosidic linkage. Disaccharides may, for example, be composed of twoidentical monosaccharides as in maltose, or may be composed of twodissimilar monosaccharides as in sucrose or in lactose (milk sugar),which is made up of a D-galactose and a D-glucose unit. Suitabledisaccharides for use in the practice of this invention include:sucrose, maltose, lactose, and cellobiose.

Oligosaccharides are water-soluble polymers consisting of 2-10monosaccharide units. Oligosaccharides can be further classified ashomopolymers containing only one type of monosaccharide, orheteropolymers containing several different kinds of monosaccharides.Examples of oligosaccharides suitable for use in the practice of thisinvention include: stachyose, a naturally occurring tetrasaccharide,maltopentaose, a five monosaccharide unit oligosaccharide,cyclomaltohexaose, a cyclic polysugar consisting of six monosaccharideunits, maltoheptaose, and maltotriose.

The water-absorbing composition of this invention can be prepared usingany suitable blending method such as described in the Examples whichfollow. After the water-absorbing composition is prepared, but typicallybefore it is cured but in some instances as it is curing, it isprocessed into any desired form using conventional methods offabrication. For example, the water-absorbing composition can besubjected to casting; spray drying; air-assisted spray drying; airattenuation; wet, dry or flash spinning; and the like. The selection ofthe process is typically dictated by the shape or form needed for enduse. Forms that the water-absorbing composition may be fabricated intoinclude films or sheets, powders and granules, fibers and any form intowhich fibers can be processed such as for example milled fibers, choppedfibers, fluff or bulk fibers, strands, yarns, woven fabrics, non-wovenmats and the like using a variety of methods, including twisting,beaming, slashing, warping, quilling, severing, texturizing, weaving,knitting, braiding etc.

While not meaning to be limited to any theory, the disaccharide oroligosaccharide compound is believed to serve as a high temperature,slow-reacting, cross-linking type agent for the copolymer particlesresulting in the formation of covalent cross-link type bonds uponcuring. For example, it has been found that, if a partially neutralizedstyrene-maleic anhydride copolymer is blended with sucrose to form awater-absorbing composition according to this invention, a temperatureabout 150° C. or higher is typically required to achieve cure.Similarly, if a partially neutralized ethylenemaleic anhydride copolymeris employed, a temperature of 140° C. or higher is typically needed toachieve cure. And, if a partially neutralized isobutylene-maleicanhydride copolymer is employed, a temperature of 200° C. or higher istypically needed to achieve cure.

Without meaning to limit the invention, the water-absorbing compositionsof this invention are particularly well suited for being made intofibers because of the wide time and temperature ranges over which theycan be shaped. More specifically, the water-absorbing compositions ofthis invention can be formulated to cure at temperatures within therange of from about 140° C. to about 250° C. or higher and possess shelflives in excess of two months. Hence, the water-absorbing compositionsof this invention can be easily made into fibers using conventionalfiber-forming methods and equipment. Moreover, no post-treatment (e.g.,a salt-forming reaction as taught in U.S. Pat. No. 3,983,095) of thecured fiber products is required.

The water-absorbing compositions of this invention and articles ofmanufacture into which the compositions are incorporated are suitablefor use in a wide range of absorptive functions. In general, thearticles into which the water-absorbing compositions are incorporatedserve the function of supporting the composition and presenting it in aform adapted for absorptive end use. Means to support and present thecomposition for absorptive use include, but are not meant to be limitedto bandages, surgical and dental sponges, tampons, sanitary napkins andpads, disposable diapers, meat trays, pads for absorption ofperspiration, and the like.

In one embodiment, a water-absorbing composition of this invention isincorporated into a disposable diaper, using conventional fabricationmethods to form a diaper composite having the following typical layers:(1) an outer layer (away from the body) of impermeable polyethylenefilm; (2) a first cellulosic pulp layer superimposed on the film; (3) alayer of (i) a cured water-absorbing composition of this invention inthe form of, for example, fluff, a fibrous mass, a non-woven fiber mator a woven fabric; or (ii) a layer comprising a blend of a curedwater-absorbing composition of this invention and another fluffconventionally employed in diapers; (4) an optional, second cellulosicpulp layer; and (5) an inner permeable polyethylene film layer.

Fibers made from the water-absorbing compositions of this invention areparticularly suitable for absorbent applications. It is well known thata mass of fibers provides a large surface area for contact with theliquid material to be absorbed. Fibers as compared to powders can alsobe more easily confined within the article into which they areincorporated.

The following examples serve to further demonstrate the invention.

EXAMPLE 1

This example demonstrates the preparation of a water-absorbingcomposition of the invention using ISOBAM 10 isobutylene/maleicanhydride copolymer commercially available from Kuraray IsopreneChemical Company, Limited. ISOBAM 10 has a molecular weight of 170,000and a maleic anhydride content of about 59.3 weight percent (46.6 mole%) as determined by titration of maleic acid.

About 1270 g of ISOBAM 10 isobutylene/maleic anhydride copolymer andabout 2007 g of demineralized water were added to a mixing vessel withagitation and the vessel contents were heated to about 90° C. At atemperature of about 90° C. about 658 g of a 50% sodium hydroxidesolution prepared from 98.9% pure sodium hydroxide pellets were slowlyadded to the mixing vessel over a one hour period with agitation. Afterthe addition of the sodium hydroxide solution, agitation was continuedfor about 12 hours at 90° C. to complete the reaction.

The pH of the solution was found to be 6.5 and the neutralizationreaction was calculated to have converted about 53.5% of the pendantcarboxylic acid units on the 46.6 mole % anhydride units intocarboxylate sodium salt units. The balance of the pendant units wereconverted to carboxylic acid units.

About 311 g of the above aqueous solution of the partially neutralizedisobutylene/maleic anhydride copolymer were mixed with about 7.0 gsucrose and stirred for about 30 minutes. After stirring, the solutionwas heated to drive off excess water and to provide a solution havingapproximately a 45% solids content suitable for fiber formation. Thecomposition (I) contained 7 phr of sucrose based on the weight of theisobutylene/maleic anhydride copolymer. About 10 micron diameter fiberswere prepared from the composition using a dry spinning process. Theresultant fibers were divided into four portions and separately cured byheating in a hot air circulating oven at various cure conditions. Eachsample of fibers was tested to determine Swell Index and PercentSolubility using the test procedures described below. The test resultsare shown in Table 1.

                  TABLE 1                                                         ______________________________________                                        Fibers of Composition                                                                        I       I        I     I                                       ______________________________________                                        Cure Temperature (°C.)                                                                200     210      210   210                                     Cure Time (Minutes)                                                                          30      20       30    45                                      Swell Index (g/g)                                                             Atmospheric Pressure                                                                         43.4    30.7     31.7  26.8                                    0.5 psi        29.4    22.5     24.2  20.8                                    % Solubility   14.0    8.4      11.5  12.5                                    ______________________________________                                    

Swell Index

This test procedure is described in U.S. Pat. No. 4,45455 the teachingsof which are incorporated herein by reference thereto. The testprocedure and equipment used herein were modified slightly as comparedto the procedure and equipment described in U.S. Pat. No. 4,454,055.

To determine the Swell Index at atmospheric (room) pressure, about 0.2to 0.3 g of the water-absorbing composition to be tested is placed in anempty W-shaped tea bag. The tea bag containing the composition isimmersed in brine (0.9 wt. % NaCl) for 10 minutes, removed and allowedto sit on a paper towel for 30 seconds to remove surface brine. TheSwell Index of the composition, that is, the units of liquid absorbedper each unit of sample is calculated using the following formula:##EQU1##

To determine Swell Index under pressure, the following modifiedprocedure was used.

After the tea bag containing the sample composition is immersed in brineand surface brine is removed, it is immediately placed in a 16 cm IDBuchner funnel fitted with a 2000 ml sidearm vacuum filter flask andconnected to a manometer. Then, a piece of dental dam rubber sheeting issecurely fixed over the mouth of the funnel such that the sheeting justrests on the tea bag. Next, a vacuum sufficient to create the desiredpressure is drawn on the flask for a period of five minutes, and, theSwell Index under pressure is calculated using the above formula.

Percent Solubility

About 0.5 g of the water-absorbing composition sample to be tested isdispersed in about 150 g of brine (0.9 wt. % NaCl) at room temperaturefor 20 minutes with occasional gentle agitation. After 20 minutes, themixture is filtered through a 150 micron polypropylene screen. Next, thefiltrate is dried to a constant weight in an oven and the weight ofsoluble composition determined by subtracting the weight of the NaClfrom the total weight of the dry filtrate. Percent solubility is thendetermined using the following formula: ##EQU2##

EXAMPLE 2

Using substantially the procedure of Example 1, about 314 g of theaqueous solution of the partially neutralized isobutylene/maleicanhydride copolymer produced in Example 1 were mixed with about 10.1 gof sucrose and concentrated to give a 45% solids composition(Composition II) containing 10 phr of sucrose based on the weight of theisobutylene/maleic anhydride copolymer. About 10 micron diameter fiberswere prepared from the composition as described in Example 1. Theabsorbency of the fibers and the effect of cure conditions on samples ofthe fibers are shown in following Table 2.

                  TABLE 2                                                         ______________________________________                                        Fibers of Composition                                                                         II        II      II                                          ______________________________________                                        Cure Temperature (°C.)                                                                 200       210     210                                         Cure Time (Minutes)                                                                           30        20      30                                          Swell Index (g/g)                                                             Atmospheric Pressure                                                                          40.6      39.6    31.6                                        0.5 psi         29.2      25.7    18.4                                        % Solubility    13.4      13.3    11.5                                        ______________________________________                                    

EXAMPLE 3

This example demonstrates the preparation of a copolymer ofstyrene/maleic anhydride suitable for use in this invention.

A solution of about 240 g of maleic anhydride, about 255 g of styrene,and 2370 ml of methyl ethyl ketone was prepared and introduced into aone gallon stirred reactor at room temperature under a nitrogenatmosphere. Free radical polymerization was initiated by charging about8.20 g of VAZO 65 polymerization initiator (asoisobutyronitrile, E. I.DuPont) into the reactor. The polymerization reaction was conducted forabout 24 hours at a temperature of aboout 55° C., and thentetrahydrofuran was added to dilute the reactor contents.

The resulting polymerization product, a copolymer of styrene and maleicanhydride, was recovered by precipitation into methanol with high speedstirring. The copolymer was dried overnight at 30° C. in a vacuum oven,and then at 90° C. for about one hour. About 499 g of copolymer wererecovered.

The dried styrene/maleic anhydride copolymer was analyzed by titrationof maleic acid and found to contain 43 mole percent maleic anhydride(41.7 wt. %). The balance of the copolymer was styrene. The copolymerwas tested and found to have a glass transition temperature of 234° C.by differential scanning calorimetry and a peak molecular weight of108,000 by gel permeation chromatography using polystyrene standards.

EXAMPLE 4

This example demonstrates the preparation of a water-absorbingcomposition of the invention using the styrene/maleic anhydridecopolymer of Example 3.

About 30 g of copolymer and about 300 g of demineralized water wereadded to a mixing vessel with agitation and the vessel contents wereheated to about 90° C. At a temperature of about 90° C. about 10.2 g ofa 50% sodium hydroxide solution prepared from 98.9% pure sodiumhydroxide pellets were slowly added to the mixing vessel over a one hourperiod with agitation. After the addition was completed, agitation wascontinued for about one hour and the copolymer dissolved into solution.

The neutralization reaction was calculated to have converted about 50%of the pendant carboxylic acid units on the 43 mole % anhydride unitsintc carboxylate sodium salt units. The balance of the pendant unitswere converted to carboxylic acid units.

About 3 g of sucrose (table sugar) were added to the solution withstirring at 90° C. for a few hours to drive off excess water and toprovide solution of approximately a 45% solids content suitable forfiber formation. The composition (III) contained 10 phr of sucrose basedon the weight of the styrene/maleic anhydride copolymer. About 1-5micron diameter fibers were prepared from the composition using a dryspinning process. The resultant fibers were cured by heating at 160° C.for 30 minutes in a hot air circulating oven. The sample of fibers wastested to determine Swell Index and Percent Solubility. The test resultsare shown in Table 3.

                  TABLE 3                                                         ______________________________________                                        Fibers of Composition                                                                            III                                                        ______________________________________                                        Cure Temperature (°C.)                                                                    160                                                        Cure Time (Minutes)                                                                              30                                                         Swell Index (g/g)                                                             Atmospheric Pressure                                                                             32.1                                                       0.5 psi            20.5                                                       % Solubility       13.0                                                       ______________________________________                                    

It will be evident from the foregoing that various modifications can bemade to this invention. Such, however, are considered as being withinthe scope of the invention.

What is claimed is:
 1. A composition which is water-absorbent uponcuring comprising:(a) a copolymer containing from about 25 to about 75mole percent recurring units of at least one α, β-unsaturated monomerbearing at least one pendant unit selected from the group consisting ofcarboxylic acid units and derivatives of carboxylic acid units and fromabout 75 to about 25 mole percent recurring units of at least onecopolymerizable comonomer, wherein from about 20 to about 80 percent ofthe total pendant units introduced through the recurring units of the α,β-unsaturated monomer must either be carboxylic acid units or must beconverted into carboxylic acid units, and wherein from about 80 to about20 percent of the total pendant units must either be carboxylate saltunits or must be converted into carboxylate salt units; and (b) at leastone carbohydrate compound selected from the group consisting ofdisaccharides and oligosaccharides.
 2. The composition of claim 1 inwhich said copolymer contains from about 35 to about 65 mole percentrecurring units of said at least one α, β-unsaturated monomer and fromabout 65 to about 35 mole percent of said at least one copolymerizablecomonomer.
 3. The composition of claim 1 in which said copolymer is anequimolar copolymer.
 4. The composition of claim 1 comprising in weightpercent from about 80 to about 99 of said copolymer and from about 1 toabout 20 of said carbohydrate compound.
 5. The composition of claim 1comprising in weight percent from about 85 to about 95 of said copolymerand from about 5 to about 15 of said carbohydrate compound.
 6. Thecomposition of claim 1 in which said copolymer is a copolymer of styreneand maleic anhydride.
 7. The composition of claim 1 in which saidcopolymer is a copolymer of ethylene and maleic anhydride.
 8. Thecomposition of claim 1 in which said copolymer is a copolymer ofisobutylene and maleic anhydride.
 9. The composition of claim 1 in whichsaid compound is sucrose.
 10. The composition of claim 1 in which saidcompound is lactose.
 11. The composition of claim 1 in which saidcompound is maltose.
 12. The composition of claim 1 in which saidcompound is cellobiose.
 13. The composition of claim 1 in which saidcompound is an oligosaccharide consisting of 2-10 monosaccharide units.14. A method of producing a water-absorbing composition comprising thesteps of:(a) preparing a blend of (i) a copolymer containing from about25 to about 75 mole percent recurring units of at least one α,β-unsaturated monomer bearing at least one pendant unit selected fromthe group consisting of carboxylic acid units and derivatives ofcarboxylic acid units and from about 75 to about 25 mole percentrecurring units of at least one copolymerizable comonomer, wherein fromabout 20 to about 80 percent of the total pendant units introducedthrough the recurring units of the α, β-unsaturated monomer must eitherbe carboxylic acid units or must be converted into carboxylic acid unitsand wherein from about 80 to about 20 percent of the total pendant unitsmust either be carboxylate salt units or must be converted intocarboxylate metal salt units; and (ii) at least one carbohydratecompound selected from the group consisting of disaccharides andoligosaccharides; and (b) curing the resulting blend.
 15. The method ofclaim 14 comprising the step of forming the blend into a shaped articleafter the blend is prepared but before it is fully cured.
 16. The methodof claim 15 in which the blend is formed into fibers.
 17. The method ofclaim 15 in which the blend is formed into a powder.
 18. The method ofclaim 15 in which the blend is formed into a film.
 19. The method ofclaim 14 in which said curing is induced by heating the blend.
 20. Anarticle of manufacture comprising a cured water-absorbing compositionand a means for supporting said composition for absorption usage,wherein said water-absorbing composition comprises a blend of:(a) acopolymer containing from about 25 to about 75 mole percent recurringunits of at least one α, β-unsaturated monomer bearing at least onependant unit selected from the group consisting of carboxylic acid unitsand derivatives of carboxylic acid units and from about 75 to about 25mole percent recurring units of at least one copolymerizable comonomer,wherein from about 20 to about 80 percent of the total pendant unitsintroduced through the recurring units of the α, β-unsaturated monomermust either be carboxylic acid units or must be converted intocarboxylic acid units, and wherein from about 80 to about 20 percent ofthe total pendant units must either be carboxylate salt units or must beconverted into carboxylate metal salt units; and (b) at least onecarbohydrate compound selected from the group consisting ofdisaccharides and oligosaccharides.
 21. The article of manufacture ofclaim 20 in which said means for supporting said composition is adisposable diaper.
 22. The article of manufacture of claim 20 in whichsaid means for supporting said composition is a tampon.
 23. The articleof manufacture of claim 20 in which said means for supporting saidcomposition is a sanitary napkin.
 24. The article of manufacture ofclaim 20 in which said means for supporting said composition is asurgical or dental sponge.
 25. The article of manufacture of claim 20 inwhich said means for supporting said composition is a bandage.
 26. Thearticle of manufacture of claim 20 in which said composition isincorporated into said means for supporting in a fibrous form.
 27. Thearticle of manufacture of claim 20 in which said composition isincorporated into said means for supporting in the form of powder. 28.The article of manufacture of claim 20 in which said composition isincorporated into said means for supporting in the form of film.
 29. Amethod of enhancing the water absorption characteristics of an articleof manufacture which comprises the step of incorporating into saidarticle a cured water absorbing composition which comprises a blendof:(a) a copolymer containing from about 25 to about 75 mole percentrecurring units of at least one α, β-unsaturated monomer bearing atleast one pendant unit selected from the group consisting of carboxylicacid units and derivatives of carboxylic acid units and from about 75 toabout 25 mole percent recurring units of at least one copolymerizablecomonomer, wherein from about 20 to about 80 percent of the totalpendant units introduced through the recurring units of the α,β-unsaturated monomer must either be carboxylic acid units or beconverted into carboxylic acid units, and wherein from about 80 to about20 percent of the total pendant units must either be carboxylate metalsalt units or be converted into carboxylate metal salt units; and (b) atleast one carbohydrate compound selected from the group consisting ofdisaccharides and oligosaccharides, said composition being incorporatedinto said article in an effective amount to enhance at least onewater-absorbing characteristic of said article as compared to thewater-absorbing characteristics of the article in the absence of thecomposition.
 30. The method of claim 29 in which said article ofmanufacture is a disposable diaper.
 31. The method of claim 29 in whichsaid article of manufacture is a tampon.
 32. The method of claim 29 inwhich said article of manufacture is a sanitary napkin.
 33. The methodof claim 29 in which said article of manufacture is a disposablebandage.
 34. The method of claim 29 in which said composition isincorporated into said means for supporting in a fibrous form.
 35. Themethod of claim 29 in which said composition is incorporated into saidmeans for supporting in the form of powder.
 36. The method of claim 29in which said composition is incorporated into said means for supportingin the form of film.
 37. A method of absorbing water and electrolytesolutions comprising the step of contacting the water or electrolytesolution to be absorbed with a cured water-absorbing compositioncomprising a blend of:(a) a copolymer containing from about 25 to about75 mole percent recurring units of at least one α, β-unsaturated monomerbearing at least one pendant unit selected from the group consisting ofcarboxylic acid units and derivatives of carboxylic acid units and fromabout 75 to about 25 mole percent recurring units of at least onecopolymerizable comonomer, wherein from about 20 to about 80 percent ofthe total pendant units introduce through the recurring units of the α,β-unsaturated monomer must either be carboxylic acid units or must beconverted into carboxylic acid units, and wherein from about 80 to about20 percent of the total pendant units must either be carboxylate saltunits or must be converted into carboxylate salt units; and (b) at leastone carbohydrate compound selected from the group consisting ofdisaccharides and oligosaccharides.